Most polymers are generally thought to be heat and oxygen sensitive and tend to degrade to form products which have an adverse effect on their color as well as their physical properties. Bisphenols which are important in the preparation of epoxy resins and polyesters, are also known to be heat and oxygen sensitive and form degradation products which adversely affect the polymers subsequently made from them. Thus, bisphenol A is known to decompose with heat to form phenol and p-isopropylidene phenol. Additional heating can cause formation of complex non-volatile compounds. These degradation products, even in small concentrations, can cause a lowering of the molecular weight of polyesters. Color producing bodies can cause undesirable color in the bisphenol itself during its purification and in the epoxy resins and/or polyesters since both purification and manufacturing processes involve heating. The stabilization of polymers is believed to be achieved by incorporating a primary radical scavenger, usually a phenolic derivative. To combat the oxidation one must use also a hydroperoxide decomposer to be used together with the radical scavenger. Representative of hydroperoxide decomposers are thioesters and phosphites, such as dilaurylthiodipropionate and tri(nonylphenyl)phosphite. One reference in the J. Appld. Polym. Sci., Vol. 27, 951-955 (1982) reports the investigation of a diphosphonite* as both a hydroperoxide decomposer and a primary radical scavenger. The presence of metal ions is also thought to have an adverse affect on the color of bisphenols, probably by promoting degradation. Various other additives have been employed to inhibit the formation of the degradation products. Thus, alkaline earth phosphates, stannous oxide and oxalate, tin powder and tin dioxide, terephthalic and isophthalic acids, oxalic, sebacic and adipic acids and boron and antimony trioxides and their mixtures are taught as useful additives for providing thermal stability to bisphenols in British patent 890,432. Another patent, British 1,022,583, teaches that improved color stability is provided by the incorporation of oxalic, citric or tartaric acids or their alkali metal or ammonium salts during the bisphenol manufacturing process. The acids themselves or their ammonium salts are preferred and they may be added with the reactants or after the reaction is complete, but before the bisphenol is separated from the reaction mixture. U.S. Pat. No. 3,629,339 teaches the stabilization of phenols and bisphenols with an inorganic arsenic compound such as arsenic trioxide or ammonium and alkali metal arsenites. U.S. Pat. No. 4,160,110 teaches that various phthalic anhydrides are useful as distillation inhibitors against degradation of bisphenols. Thus, phthalic anhydride itself and tetrahydrophthalic anhydride are indicated as useful. Japanese patent 48097854 discloses stabilizing bisphenol A by distilling it in the presence of a polypropylene glycol, epoxy soybean oil, 2,2-bis-(p-glycidylphenyl)propane or a glycerol poly(oxypropylene) adduct. Bisphenols are stabilized against thermal decomposition by incorporating therein a quaternary aliphatic ester of ortho titanic acid according to the teachings of U.S. Pat. No. 4,359,590. A Japanese Kokoku Application No. 43-80421 teaches that the heat stability of bisphenol A can be improved by adjusting the pH to between 2.0 and 5.0 and adding a weak acid such as glycolic, thioglycolic and polyphosphoric acid. Among other acids tested in addition to the above for comparative purposes in the Japanese Patent Application were phosphorous, boric and lactic, none of which were considered to be effective. The lactic acid was no better than the uninhibited product with respect to color under conditions employed in the Japanese Patent Application. FNT *The inhibitor referred to is tetrakis(2,4-di-tert-butylphenyl)4,4'biphenylyene diphosphonite, also known as P-EPQ.